Transferring liquid product from large volume storage tanks into tank trucks or rail cars involves moving the liquid product through a fixed pipeline riser to storage containers of various sizes and orientations located in or on the tank trucks or rail cars. The various configurations of tank trucks and rail cars may require a flexible fluid transfer system such as a loading arm assembly. The loading arm assembly is a section of pipeline capable of handling high flows and line pressures that can be moved both vertically and horizontally to accommodate transport vehicles of various configurations.
One particular method of transferring liquid product through the loading arm involves using a bottom loading coupler to couple the loading arm to the storage container of the transport vehicle. The bottom loading coupler attaches to the lower portion of the vehicle storage container and, therefore, does not require personnel to climb to the top of the storage container in order to facilitate liquid transfer. The bottom loading coupler generally mates with a bottom loading adapter. A poppet valve assembly located in the body of the bottom loading coupler may be used to control the flow of liquid into the storage container. The poppet valve assembly may be actuated using a handle positioned on the outside of the body of the bottom loading coupler. The handle is generally coupled to the poppet valve assembly via a shaft which extends through a bushing positioned in a hole extending through the body of the bottom loading coupler. The bushing, which may include one or more seals, provides a bearing surface for the shaft and may seal the shaft such that gas or liquids transferred through the body of the bottom loading coupler do not leak out around the shaft. The bushing may be held in the hole with pins inserted through holes in the body tangential to the hole such that the pins contact and interfere with the outside diameter of the bushing thereby holding the bushing in place.
Because the bushings are a bearing surface, the bushings are susceptible to wear and thus are periodically replaced. Replacement of the bushing requires that the pins be removed from the body which is usually accomplished by driving the pin from its hole. Driving the pin from the hole may be a difficult operation necessitating removal of the bottom loading coupler from the loading arm assembly. Further, the driving the pin from the hole may damage the holes and or body of the bottom loading coupler thereby adversely affecting operation of the bottom loading coupler.
Accordingly, a need exists for alternative handle shaft assemblies and shaft bearing surfaces for use in bottom loading couplers.